Global warming has severely impacted the supply of fresh water in many parts of the world. Coastal communities have resorted to salination plants while those in the far interior have no option but to extract water from the air. Most of these techniques are energy-intensive or only work under certain conditions. Now, a new technology developed by researchers at ETH Zurich can help humanity access fresh water 24 hours a day and without spending any energy.
The technology might not look so sophisticated at first, and one might just say that it's just another regular glass pane. But only the researchers who developed it will tell you that this glass pane is coated with special polymers and silver layers that give the glass properties to reflect solar radiation and also emit heat directly into outer space.
To do so, the glass pane is housed in a special cone-shaped radiation shield that prevents heat and solar radiation from hitting it back. It also allows the glass pane to radiate its own heat outward at an infrared wavelength so that it is not trapped in the Earth's atmosphere. This allows the glass pane to cool as much as 59 degrees Fahrenheit (15 degrees Celsius) below the ambient temperature and trap moisture from the air on the underside.
The researchers have applied a novel water-repellent coating to the underside of the pane which facilitates the formation of water beads that run off the surface.
The entire process does not require any energy input and works great even during the day, thanks to the radiation shield.
Pilot studies showed that the device could harvest up to 1.8 fluid ounces (0.53 decilitres) of water per square feet (one square meter) of pane surface per hour, in ideal conditions.
"This is close to the theoretical maximum value of 2.03 ounces (0.6 decilitres) per hour, which is physically impossible to exceed," said Iwan Hächler, a doctoral student at ETH Zurich, and one of the authors of the study that was published in Science Advances.
Producing coated glass panes is a fairly simple process and, we would see water harvest farms built by linking a series of such condensers together in the near future.